ISO27001:2013 Certified Supplier

How Seriously Do We Take Information Security?

We’re an IT company: you’d expect us to say that we take information security seriously – and we do.

But We Would Say That, Wouldn’t We?

We don’t think you should have to take our word for it, so back in 2014 we embarked upon the journey to certification under ISO27001:2013, the Information Security standard. We examined, refined, documented and tested every aspect of Information Security, both within Tiger Computing and extending to how we manage and support our clients’ systems. In May 2015, we put ourselves to the test. We were independently audited and were assessed and certified as meeting the requirements of ISO27001:2013.

What Does This Mean For You?

It means that you can rest assured that we take Information Security seriously; that we will continue to refine and improve our Information Security policies; and that we will be independently audited annually to confirm that we are maintaining the required high standards of ISO27001:2013.

What’s Next?

We will continue to grow our support, management and monitoring infrastructure to ensure that our clients have the very best availability of your systems – and we’ll continue building our team of the best Linux experts in the UK.

NEWS & BLOG

When all else fails

POSTED: 8th January 2019

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Some operating systems have a reputation for needing regular reboots to keep them happy. Rebooting a Linux server is thankfully very rare, but occasionally they do get so stuck that only force will do. Let’s look at three methods of regaining order, by increasing order of desperation.

Of course a reboot will usually mean a service interruption. That can be mitigated by using high-availability techniques, so that even emergency maintenance for one server doesn’t compromise the service overall.

The gentle way: requesting a reboot

Most Linux systems are configured so that the key combination Ctrl+Alt+Del triggers a shutdown and restart procedure. Just like in a shutdown, applications get a small amount of time to clean up and make sure their data is safe before being closed. If an application isn’t responding, it gets stopped forcefully after a timeout.

This doesn’t work if you don’t have physical access to the server and a keyboard plugged into it, though. The best you can do in a remote situation is shutdown -r now or reboot, which both assume that the system is responsive enough to acknowledge the command.

Another alternative is to have a remote network-accessible unit simulate a keyboard, independent from the problematic server. That allows you to ‘press’ Ctrl-Alt-Del remotely, but at the risk that there’s another piece of hardware involved.

The abrupt way: triggering a hardware reset

You might have wondered what the mysterious SysRq key is used for: it’s to send instructions directly into the Linux kernel and bypass the whole of userspace, avoiding a misbehaved application eating the keyboard input.

There are several useful key combinations to get the kernel’s attention; they all start by holding down Alt and SysRq and then simultaneously pressing:

R: switch the keyboard from raw mode, ready for further instructions

E: send a graceful TERM signal to all processes except init

I: send a forceful KILL signal to all processes except init

S: sync all filesystems to disk

U: mount all filesystems read-only

B: trigger a hardware reset

Use the signals in this order for an orderly shutdown, but only from the physical console. If you have remote access only, skip out the ‘E’, ‘I’, and ‘U’ steps – otherwise your remote shell will be terminated before you reach ‘B’!

The downright rude way: pull the power

If all else fails, unplugging the server is a sure-fire way to get control back. This is the most risky though, because the OS has no opportunity to make sure data is safely on disk before resetting hardware.

Most distributions will automatically try to recover filesystems during the next boot and more often than not they are successful, but it’s never a guarantee.

Remote power control units can be useful if you don’t have physical access, although they also suffer from the same redundancy problem as remote keyboards.